Aerospace Use Of Hexavalent Chromium And Soluble Nickel In Relation To REACh

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18 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Aerospace Use Of Hexavalent Chromium
And Soluble Nickel In Relation To REACh

7
th

October 2009

From a combined Goodrich and Rolls
-
Royce review of the
implications of REACh for the aircraft industry


Goodrich: J Henshaw; G Armstrong

Rolls
-
Royce: A Page; J Watson; C Phillips; A Phillips

© Goodrich Actuation Systems Limited 2009







CONFIDENTIAL

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© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Chromium And Nickel Compounds In Current
Products



The Aerospace industry



Currently uses hexavalent chrome and nickel compounds in a number
of flight critical applications for various reasons



Has been researching viable alternatives for many years



Has found that very few alternatives are successful in the aircraft
environment



Compared to other industries, requires a significantly longer time to
introduce changes into existing products due to the extensive testing
obligations to comply with airworthiness requirements.


3

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Chromium and Nickel Compounds In Current
Products


As an example



Components supplied for an Airbus A 320 aircraft (typically engines, flight
control actuators, landing gear etc)



Original equipment deliveries planned until at least 2018


Fleet support required until approximately 2040



Supplied products include extensive use of:


hard chrome plating; Chromic anodising; Sealing of anodising on aluminium alloys;
passivation baths for stainless steel and cadmium plating; sacrificial paints using
chrome phosphate; conversion coatings on magnesium and aluminium; nickel
plating; tribomet coatings for wear and sealing; electrochemical machining.


Problem


The above products have been fully tested and certified for flight


Changes require extensive retesting to prove that they represent a comparable
safe alternative


Introduction onto the aircraft / engine typically takes between 5 and 10 years


Assuming that the alternative has already proved to be technically capable



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© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Aerospace Equipment Sector Cr
6+

Use and Status

Substance
Process used in
Why important in Design
Status of Alternatives
Hard chrome
plating
Provides sealing surface for
hydraulic seals, wear resistance to
moving parts and corrosion
protection
Alternatives, e.g. HVOF, available for about 50% of
applications but they have to be designed in from new.
Substitution in mid life not an option.
Chromic acid
anodising
Provides best corrosion protection
of the various anodising methods
and has least detrimental effect on
fatigue properties of the base
material.
Alternatives exist for some applications and can be used
on existing designs. No alternatives are proven for
fatigue critical parts or parts made from castings.
Sealing of
anodising on
aluminium alloys
Provides the best corrosion
protection, particularly in
applications which will not be
painted for environmental and
weight benefit.
Alternatives are still being evaluated. Best candidate
requires nickel salts so no environmental advantage.
Passivation baths
for stainless steel
Used to ensure best resistance to
corrosion from stainless steels and
necessary to comply with aircraft
industry standards
Alternatives do exist but are not compliant with
international aircraft industry standards.
Passivation of
cadmium plating
Used to ensure that cadmium plated
parts meet international standard for
corrosion protection
Alternatives exist for about 70% of new designs. Not
possible to apply without equipment re-design to
producst already qualified.
Chromic Acid
Sodium
Dichromate
Note: The original substances are not present in the final product

5

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Aerospace Equipment Sector Cr
6+

Use and Status

Substance
Process used in
Why important in Design
Status of Alternatives
Corrosion
protection
Provides surfaces with corrosion
protection to guarantee component
life.
Trivalent chrome alternatives under development, but
not equivalent life nor validated in an engine
environment.
Oxidation
protection
Provides oxidation protection to
surfaces used at high temperature.
Alternatives exist for some applications based on
trivalent chrome. These can be used in existing designs
no alternatives are proven for fatigue critical parts.
Organic barrier
coatings
Corrosion protection of complex
geometries.
Some alternatives available but not validated in an engine
environment.
Two-part epoxy
paint systems
Protection against wet corrosion on
complex geometries.
Some alternatives available but not validated in an engine
environment.
Various
chromate salts
Paints, both primer
and topcoats
Used to give required corrosion
protection from paint in the aircraft
operating environment.
Alternatives available for use on some new designs but
not all. Change of paint to existing designs not yet
accepted without extensive testing.
Chrome
phosphate
6

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Aerospace Equipment Sector Nickel Use and
Status

Substance
Process used in
Why important in Design
Status of Alternatives
Abrasive coating
Provides a means to guarantee
engine performance and is essential
in achieving component lifetime
through improvements in fatigue
resistance.
No known alternatives.
Wear resistant
coatings
Provides improved wear resistance
to surfaces and guarantees
component lifetime through
mitigation of fatigue failures.
Alternatives exist for some applications and can be used
on existing designs. No alternatives are proven for
fatigue and wear resistance for critical parts.
Nickel plating
Provides the best corrosion
protection, particularly in
applications of complex geometry.
Alternatives are still being evaluated. Currently none
provide an environmental advantage.
Nickel plating
Provides the best corrosion
protection, particularly in
applications of complex geometry.
Alternatives are still being evaluated. Currently none
provide an environmental advantage.
Electrochemical
machining (ECM)
Used to provide means of machining
complex shapes.
Alternatives exist for some geometries but manufacturing
is more complex and would require re-validation.
Nickel
sulphamate /
nickel chloride
Nickel sulphate
/ nickel nitrate
Note: The original substances are not present in the final product

7

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Aerospace Equipment Sector Ni
2+
(aq) Use and
Status

Substance
Process used in
Why important in Design
Status of Alternatives
Nickel Sulphate
Nickel Hypophosphite
Nickel Phosphite
Nickel Chloride
Nickel Sulphamate
Electroless Nickel
plating
Unique as being the one hard
coating process which is electroless
and so will plate on complex and
internal geometries as there are no
electrode, electric field intensity or
line of site issues
Some potential from electroless nickel boron but as yet
not proven for endurance, and not available in supply
chain.
Nickel Acetate
Sealing of
anodising on
aluminium alloys
Provides good corrosion protection
on 7000 series alloys in a sealing
solution which does not contain
chrome 6+ ions
Alternatives are still being evaluated in same task as
that to replace dichromate sealing. So far, alternaitves
have inferior corrosion performance.
Note: The original substances are not present in the final product

8

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Example Data


Rolls
-
Royce Testing Status
For Hexavalent Chrome Replacements

0
5
10
15
20
25
30
35
40
Today's "chrome"
applications
Validated chrome-free
replacement exists
Potential chrome-free
replacements not yet
validated
No known chrome-free
replacement exists
Other aerospace companies have programmes in place with similar results

9

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Typical Uses Of Hexavalent Chrome And
Soluble Nickel

Aircraft paints

Engines

Landing gear

Primary and
secondary
flight control
actuation

10

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Materials In A Current Civil Engine

Rolls
-
Royce Example

Nickel

40%

All Others

5%

Steel

25%

Titanium

30%


Current Technology:


All steel and all aluminium parts of an
engine (the outer casing) are coated in
mixtures containing hex chrome in at
least one layer of the coating system:
Usually in all 8


10 layers.


Even if alternatives are available during
manufacture, hex chrome is needed for
product repair.


11

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Summary



Changes to products are governed by legal airworthiness
requirements which also define the requirements for retesting
when changes are made



Testing must be to the same standard and vigour as occurred for
the original aircraft / engine airworthiness approval



Safe replacements are at various stages of technical approval



Many examples exist where safe alternatives have not yet been
developed or proven



Substance elimination under REACh must take account of the
special needs of the aircraft industry due to the safety implications

12

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Conclusion


With very few exceptions, hexavalent chrome and soluble nickel are not in the final
product on aircraft. There is no exposure of them to the public. Exposures to
downstream workers and during manufacture is restricted via a highly restricted
and controlled environment. e.g. Component maintenance manuals and Nadcap



Credible alternatives have not yet reached a stage of maturity to give confidence
that they could be implemented within current estimates of the REACh time table.



With enough research work, hexavalent chrome and soluble nickel compounds
could be significantly reduced in future aircraft models provided that the
alternatives can be proven to satisfy the demanding technical standards for
airworthiness.



Existing aircraft will need to be maintained for several decades with a safe and
stable supply of spares. Validation of retrospective design changes is significantly
more challenging than new product introduction



If any of these substances are listed on REACh Annex XIV, then
the aircraft industry will require exemption for existing aircraft
programmes.

13

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Supporting Information


Additional slides with further supporting information to the earlier
tables follow this slide for use if required.

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© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Alternatives tested for hard chrome plating


WC
-
Co
-
Cr applied by HVOF spray coating


Limited application opportunities due to adverse impact on base material


Successful in some applications


Geometry constraints so not a universal substitute


Very limited availability in supply base


W
-
Co electroplated nano coating


Potential option to produce hard surfaces for seals to run on


Still in R&D phase


no commercial availability


Not proven for seal running


Diamond like carbon


Not a viable option following testing due to poor adhesion and poor endurance


required coating thickness cannot be achieved


PVD Coatings


As for Diamond like carbon


not a viable option following testing due to poor
adhesion and poor endurance


required coating thicknesses cannot be
achieved.

15

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Alternatives tested for chromic anodising


Sulphuric anodising


Coating has to be 5 times thicker than chromic for equivalent
corrosion resistance


Fatigue properties of base alloy are damaged by this process


Cannot be used on aluminium parts made from castings


Can only be used on non fatigue sensitive parts made from bar or
forging


Boric Sulphuric Anodising


Works well but still needs dichromate sealing for acceptable
corrosion resistance


Minimal reduction in fatigue properties


Boeing IPR so cannot be used on Airbus products


Keronite PEO Coating


Thicker coating than chromic anodising


Claims that it does not reduce fatigue properties
-

not proven

16

© Goodrich Actuation Systems Limited 2009

CONFIDENTIAL

Alternatives for Electroless Nickel Plating


None yet evaluated


The key attribute of the electroless nickel process is that it is
electroless and so does not have the geometric constraints of
electroplating or spraying processes (edge effects and line of site
issues)


Possibility for electroless Nickel
-
Boron plating but not readily
available and not yet tested by GAS.